This invention relates to the art of transmissions and, more particularly, to a brake and clutch mechanism for use with heavy machinery such as metalworking presses.
Liquid cooled and lubricated clutch and brake drive mechanisms have been provided heretofore for use with heavy machinery such as presses. Such mechanisms generally include an output shaft, a flywheel driven by a motor, a clutch mechanism for selectively engaging and disengaging the flywheel and output shaft, and a brake mechanism for braking rotation of the output shaft when the clutch is actuated to disengage the flywheel and output shaft. A suitable liquid, such as oil, is circulated through the housing of the drive mechanism to lubricate and cool the operating parts thereof including the brake and clutch components during operation of the drive unit. Recent improvements in drive mechanisms of the foregoing character have included structural arrangements in which the flywheel is supported for rotation relative to the housing of the drive mechanism and independent of the output shaft, and the provision of pneumatically or hydraulically actuated brake and clutch operating arrangements concentric with the output shaft at one end of the drive mechanism. Examples of such drive mechanisms are shown in U.S. Pat. No. 3,835,971 issued Sept. 17, 1974 and in pending patent application Ser. No. 746,732 filed Dec. 2, 1976 Now U.S. Pat. No. 4,122,926, dated Oct. 31, 1978, both of which are owned by the Assignee of the present invention. Such drive mechanism structures provide many advantages in connection with the efficiency of clutch and brake operation, accessibility for repair and/or replacement operations, balanced loading of component parts, and structural compactness. However, the clutches in these as well as other fluid actuated mechanisms heretofore provided are designed and constructed to exert a maximum torque at a specific maximum activating force under pneumatic or hydraulic pressure. Accordingly, it becomes necessary to design a number of different clutch sizes in order to cover all press drive torque requirements for which the basic drive mechanism design is adapted to be used. Design engineering is expensive, as is the maintaining of an inventory of different clutch sizes. These expenses are not only encountered by the manufacturer, but also by the customer if different sized units are to be maintained in a standby category.
Accordingly, it becomes desirable to provide a given brake and clutch drive mechanism with the capability for modifying the torque output capacity thereof to avoid the necessity of providing two separate drive mechanism structures and the expenses encountered in connection therewith. Moreover, it is desirable to achieve this capability without increasing the overall size of the basic drive mechanism and without requiring a major disassembly and reassembly operation or the use of structurally or dimensionally modified component parts with respect to the basic structural design of the drive mechanism. In this respect, drive units have been provided heretofore which can be structurally modified to provide different clutch capabilities, but the modifications required are generally of major proportion amounting in effect to two different designs and, additionally, increase the basic unit size dimensionally. For example, such prior multiple clutch capability requires a different or extended output shaft construction and/or a different housing or support arrangement from that required for the basic drive mechanism design. Accordingly, manufacturing as well as inventory costs are not reduced or minimized, and modification of the basic drive mechanism involve a major and time consuming disassembly and reassembly operation.